1. Field of the Invention
This invention relates to an apparatus for and method of aerating water in a reservoir or pond and more particularly to an improved apparatus for and method of aerating fish ponds to simultaneously replenish dissolved oxygen in the water and to move fish from the shallow water at the edge of the pond.
2. Description of the Prior Art
Fish farming has become an important source of food and other products and is widely practiced, particularly in the temperate climate areas of the world such as found in the Southern regions of the United States where catfish farming, for example, is a rapidly growing industry. In catfish farming as currently practiced, the majority of the fish are raised in large ponds created by flooding fields which may be from one or two to twenty acres or more in size. Thus, each pond will normally contain a large number of fish and represent a very substantial investment.
Such catfish farming is normally practiced in relatively level terrain so that a large field can be flooded without requiring excessive landscaping to construct the banks, and without requiring excessive water to flood the field. Conserving water is particularly important in areas where the water must be pumped from underground wells, and the ponds generally are relatively shallow. While such large, shallow ponds are well suited for growing catfish, the dissolved oxygen in the water may become rapidly depleted under certain conditions. The conditions leading to depletion of available oxygen are generally well-known to the experienced fish farmer so that the farmer can monitor the ponds and take emergency action when necessary to aerate the water and avoid fish loss.
When the oxygen level in a fish pond becomes dangerously low, the fish tend to migrate to the shallow water adjacent the edges of the pond seeking the higher levels of oxygen resulting from aeration produced by any wave action along the banks. Unless action is quickly taken, the large concentration of fish in the shallow water may actually reduce the available oxygen and often results in the fish beaching themselves and dying. Thus, the migration of fish to the edges of the pond becomes a signal to the farmer that emergency action is required. This emergency action involves not only aeration of the pond water but also driving the fish from the edges of the pond.
Various methods have been used in the past to aerate fish ponds, one known method involving use of a pump to discharge a stream or jet of water into the air where it absorbs oxygen before falling back into the pond. This also creates turbulence in the pond, again facilitating the absorption of oxygen from the atomosphere. The pump may be fixed or portable and may take suction directly from the pond or from an alternative source such as from a well.
It is also known to use mechanical agitation or aeration devices which may be moved into the pond to agitate the water. For example, a pair of paddle wheels have been mounted on a trailer or cart which could be positioned in the water, with the paddle wheels being driven through a differential drive system from a suitable power means to both agitate and aerate the water in the vicinity of the wheels and to create a current in the pond moving away from the bank in the vicinity of the aeration apparatus.
It is also known to direct a stream of water into the shallow water portion of a pond adjacent the banks to drive fish away from the banks. This generally has been accomplished by use of pumps as generally described above.